Yieldable gearing



July 4, 1933. v. A. KJAER 1,916,482

YIELDABLE'GEARING Filed Aug. 5, 1931 s Sheets-Sheet 1 )Zjaew uwavrwa July 4, 1933. v. A. KJAER YIELDABLE GEARING 3 {Sheets-Sheet 2 Filed Aug. 5, 1951.v

f Z/A A 0 July 4, 1933. v. A. KJAER YIELDABLE GEARING 5 Sheets-Sheet 3 Filed Aug. 5, 1951 Patented my 4,11933- I 1 vreoo Karmic? coi snmempmmax' v Y'InnnABLEG A-Rme' Applicationfi1ed August5, 1931, Serial 110,655,352, and m ners-at setteinber 4,1930 v I My invention relatesto ,anEiinprovement in which rotate with a certain:irregularity, and Lpart1cu1arly chain gearings for internalcombustionengines; The said.-1rregular1ty:of the ing'of additional. tensio nsrin the chain and the second-place. therein thatthe masses driv- Y 0 an bythe chain fmay be put into vibrations 1.

owinggto the impulses rising from the irregular ty, whereby the saidmas'sesmayexert. an

injurious eifect on thev chain itself. The in-,

ventiofn; has forits-object an, arrangement by. Whichlthe CilttlIl-iSSZLVGdithG said influences.

,Regardingithe stretched part of the chain 2 between two chain Wheels, it is evident that r the chain'part has vgot a certain prolongation beyond its normal length owing .to the in- ZO fluence; from the pull at thechainfpart effect-r .ing the'transfer of the energy. When the 7 driving; chain wheelgrotates with a certain irregularity, I the; prolongation' of the chain part must vary, and it will. be' alternately greater or less ,than the prolongation,- corresponding to the mean value'jof the turning momentum. TWO different casesma-y besupposed. One case is that the'motionof the chain correspondschiefly to the motion of the *:drivingchain wheel: so that it takes place 7 practically without, natural Vibrations; In, this case the motion-canbecalculated when I the degreeof irregularity, the number of; revolutions and the diameter. ofpthe chain wheel. are known, and. it will" often be possibleto so di nension the chain that it is able-to bear" the tensions. Casesoccur, however, where-the dimensions of; chains in the market do not, suflice for: the tensions-which-may occur. It f has tobe remarked; particularly that increaS- ingthe strength of thegchain means at the same time increasing itsi weight and, con-'- sequently, ,the inertia efi'ects rising fromthe irregularity. In the-other. case longitudinal vibrations occur in; thechain parts injiaddition to theabove mentioned motion so that the'parts are alternatelyprolonged.and shortened-,,and=;if,therimpulsescaused bytheirregs f v v I QWBI" f; the lvdiameter); and. in-.. versely proportional-to the length of thel l ularity have afreq-uency which-is in resonance its numberrofrevolutions must often-vary .viz so that 'a torsional momentum (e.;. g, 1

thelength of which serves to compare the shaft portion. equivalent to the tightened I 'ch aimthe prolongation ofthe chain can, sur -1, cha n gearlngs servlng to transfer energy pass the allowed value; Inan 'internallcom from, one shaft'to, anothejnn one or both of bustion engine it cannot be avoided; because between wide limits, that vigorous vibrations,

occur in a chain driven fromthecrankshafti rotation-results,in thefirst place in .theg'rais of the engine-ifparticularmeasures are not;

torsional vibrationsthis is preferably made by comparing'each individual part,- of the, system with animaginary shaft having aa determined: diameter, 'while its length,, de-M- pends on the rigidity ,ofthe part: in question,

kgln. influencing the imaginary shaft in .its, endfaces would give a torsionahangle to' thev shaft eqfual 'to the .angleywhich thexpartgofr,

' the system would'betwisted'under the influ ence of thesam'e momentum, As theprolon i, gation orshortening of a chain part causes.

amutual turningof the driving andidriven. chains, it will be. evident thatas regardsits longitudinal vibrations the chain. part may be replaced by an imaginary shaft'portion,

rigidity of the chain with the rigidityof; the other partsofthe system, which are also supposed. to be replaced. by shaft. portions 1' having the same. diameter; vThe lengthofthe chain part as "to the vibrations is designated; hereafter as. the reduced length of the chain,

and similarly the length of the imaginary r I shaft portions replacing the otherparts of the system is calledithereduced length ofgthe I partsin question, Regarding now a shaft. portion upon which a. motion having I a a cer- V tain irregularity is imposed at one end, and

at the other end of Which-is placed a mass having the momentum-of inertia I, this mass will/cause a reaction atjthe-first mentioned end appearing calculation .to the I propertional' chiefly tothe rigidity ofrthe shaft shaft. Thus the reaction will be small when the length of the shaft portion is great, and consequently a long shaft portion causes dynamically seen a separation between the mass and the place where the motion is imposed to the shaft portion. Now the invention resides therein that by means of an elastic member having a great reduced length the chain is separated either from the driving shaft or from the driven shaft or from both), or, in other words, that an elastic mom her having a greatly reduced length relatively to the reduced length of the chain is inserted in one or bothof theshafts. When the elastic member is inserted in the driving" shaft. the above mentioned momentum of inertia I hecomes equal to the momentum of inertia of the chain with its chain wheels, the driven shaft and the massesrotating therewith, wher as when the elastic member is inserted in the driven shaft 1 becomes only the momentum of lnertia of the masses driven by the chain.

By this arrangement is obtained that the chain either is separated dynamically seen) from the shaft that rotates with irregularity and is, therefore, source of vibration creat ing impulses, or is separated from the rotatingmasses which may cause injurious reactions when they are made to vibrate. E en if the device according to the invention reduces thus the vibration creating impulses influencing the chain, care must, however, preferably be taken that the natural vibration frequency of the whole system does not barmonize with the impulses, which may e. g.

be obtained by correctly dimensioning the ch ain gearing with th e elastic member and the rotating parts. It can, however. also be ob tained thereby that instead of having a constant reduced length the elastic member is so arranged that its reduced length. varies periodically but in such way that the greatest value of the reduced length is great in rela.-' tion to the reduced length of the chain. Here by is obtained first that the rotating mass-es driven through the elastic member do not get any distinct natural vibration frequency so that they are prevented from reacting on the chain with vibration creating impulses. Secondly is obtained that the whole system consisting of the chain and all rotating parts does not get any distinct natural vibration fre quency. Beside the elastic member a friction clutch is preferably employed. the enacting coupling faces of which are so pressed together that slip occurs between them if the turning momentum exceeds a predetermined value determined under consideration of the strength of the clutch elements. The turn .1 momentum is exceeded when the shaft or chain is subjected to vibrations which may arise, for instance, by reason of the wholesystem consisting of the chain and all rotating parts getting into vibrations, which does not, however, normally occur namely because of the employment of the elastic member according to the invention. As stated above, the invention is particularly applicable to internal combustion engines, especially such where the combustion air is previously compressed by means of a blower drawn directly from the crankshaft before being introduced in the engine cylinders. It is'difficult to employ rapidly running blowers in slowly running internal combustion engines, as this would require a transmission between the crank shaft and blower shaft increasing highly the velocity and, consequently, also both the injuriouseffect of the irregularity of. the crank shaft and. the reaction of the blower rotor on the chain. Relatively slowly runniug blowers must, therefore be employed, the rotors of whiehha ve a relatively great extent and, in consequence thereof, a considerable weight. If the blower should be dimensioned so as to deliver the entire quantity of air consumed bythe engine, the rotor would get'so large dimensions that the construction of a chain gearing would cause con siderable difficulties, even withthe use of the invention. It is, therefore, very advantageous tense in suchinternal combustion atmosphere during the suction stroke. Hereby is obtained a reductionof the yielding of the blower with about 50% and of the dimensions, so that the blower can be driven directly from themcrank shaft by a chain of reasonable dimensions. The invention is illustrated in the accompanying drawings whereon Fig. 1 shows afour-stroke internal combustionengineworking with supercharge by means of a blower driven by a chain gearing according to theinvention, the engine being represented in elevation as seen from one end, Fig. 2 is a side view of a part there of, Fig. 3 is a fragmentary View similar to F 2 of another constructional form of the invention, Fig. 4 illustrates a further construction of a device according to the invention, Fig. 5 is an enlarged detail sectional view of'the clutch shown in Fig. 2, and Fig. 6 is a side View with part ofthe cover removed. In Figs. 1 and 2, the reference characters 2 and 3 designate two Roots blowers supported on the framework 1 of the engine and driven from the main shaft 5 of the engine by means of a chain 4 which passes over a jockey pulley or tensioning roller 6 and a guide roller 7. The two blowers 2, 3 have a common shaft 8 provided with a chain wheel 9 around which At'each end, of the Y hammerllefor: theiblowe r 3 is; outline by;dottedlinesa-Q'l heclutches ilmillLwhich r c r v v reception of springs :31' -"llhe' deviceio'p'erates r are identical in construction consist of springs;

r :14 and-friction elements l2 andt l3havingzg 5 double conicalg'fiiction surfaces which are pressed against each yothjer with; suehza: pres i sin epv that the power ...r',equi red' to drive- 'ath'e: blowercan betransmittedby'tHei coaeting frictionfaces; According to 5 thelinvention mi the springs, 14 are so adj llSteCl: thattheir re duced rlengthfis-great in relation: to the re,-:: 'ducedlength ofthe chain; Furthermore ithe arrangement is-prefer'ably sothafithe' natural v vibration ffrequency of the r .enti re isystem= 155? (crankshaft chain; blower. shafts and masses connected therewith). isnot in resonance with" r workz llzhevibr-ations imparted to"thecl11tchthe yibration creating impulsesin; the engine n -S0 that there" is no resonance between i aforesaid impulses and the naturalfvibrati'onifv pefrequencyz of 'thechain 24, vshaft18 and --roto'rs of the blowers-2 3, the conditions beingsuch thatvibr'ationsmay possibly occur inthe last mentioned system, without however requir in-g torsional vibrations to occur inthe crank F shaft. The cramping pressure between-the coacting'faces of the clutch parts 12, 13 is not ,lgre'ater than to allow slip between them, if

the torsional momentum exceeds a'predeter- In mined value determinedunder consideration '7 'of the strength of theelements. This may occur when the engine fworksfiwithnumbers 1,-of revolutions differing from the normal one,

as in this case there isa possibili'ty'of reson nance'between the vibration'creating'impulses' -and the-- natural vibration frequency of the sys'tem. The engine is furthermore so var- 'ranged that the blowers 2', 3'drawjin airfrom the atmosphere through inlet cages {1 5, 16.7 Y 7 V and force the'compressed air through'branch Y pipes 17, 18 into a vertical'collecting pipe 19' which opens atits top into a horizontalcollecting pipe 20 from which branch pipes 21;

lead to the inlet valves QQ'ofeach-cyhnder. Part of the air charge"is,,however,@direcitly drawn into the cylindersfrom the atmosphere through an inlet cage 23, compressedair being preferably only usedfor scavenging the cylotherwise be necessary. In the constructional form shown in Fig. 3 the blower shaft 8 is driven by means of adouble chain wheel 25 connected" by a chain (not shown)"with a 3 The chain wheel 25 isconstructed in the form I of a loose toothed ring, the inner cylindrical V and ribs to the-hub 28 Vof the chain-[whee1. 'The laminated'plates 26, 27 are pressed'toe 3 gether by'means of coil springs '29, a suitable number being distributed overfv the outer;

surface bfthe f 2; heat beinglgenerated, v I Qtweeri the laminated plates, The springs 31?? are compressed, when-the laminatedfplates- 26, I i

iener gyyan'don theirsrrbsequentexpansion the "energystored-Pup during'their compress on V in lthe engine er they may: be. c au'sed by tor- Y ysional :vibrations inkthe' crank-shaft, trans- T mitt e'd 'tlrrough ithet'chainl In Fig. 4, 34' isja i vdynamo, the shaft 8- of which is driven from 'chainfand chainlwhe'el 32; .This chain wheel the interior of'theshaft 36 is a blade spring 37 which is provided centrally with a collar" being clampedbetween the two parts of which 7 the shaft 26 isco1nposed. The blade spring tenda bevel pini'on 43 engaging with afixed "ings, 42 carry the bushes 451i and thus the blade spring 37 with them'whenthecha'in wheel'32 inders and for superchargingfthem at the end- 1 I of the suction stroke. 7 This allows the blower to be far smaller dimensioned than would varies constantly so that the power trans} 1 chain wheel on the main 'shaft'of the engine,

its rigiditybeing greatest when the planeofflj plane passes through the said axis,

this arrangement of the clutch the chain,

V lates} which arei'besides vidcd with: ai-nurnberiof recesses-; for the ns t e' lm q 'us p; -We i es a i t dtiaes I grifandii "this means "paTt of the l viloratign 1 1 energy isitransformedi to friction lg o h he relativev slip 'jb'eg 27 'a-rejdisplacedrelativefto eachptherQand I absorb therebyanotherpart othe= vibration V isgiire ir up to thelaminated plates; thus ab? sorbingitheenergy n theiform of frictional and absorbed; thereby inayi ,be' eith rlocalvibrationjs setup in the chain by the impulses the main} shaft oftheiengine by means'of 213 1; is rotatably fitted on a hub keydbn'the 3 shaft 8; 'rThi'sf hub is fixed" totwo bearings in which a hollow'shaft 36 is fitted, this haftbei at right anglesto the shaft 8. In 95 38 which is fixed inthe'hollow shaft 36 by 37 hasat each end an eye 39 which by means 0G 7. of-pins 40 is fixed to bushes 41 which are rotatablyffitted inbearings 42 on the chain wheel 32. The hollow shaft 36 carries at one) 1 c I r bevel wheel-14 coaxial with the dynamo shaft I I 8. This clutch operates asfollows. The bear- I is set in rotation by'means ofthe chain gearing. Thereby the pinion -4 3 rolls on the fixed bevel wheel44- and the hlade'spring 37th ere-o fore "receives, bcside-motionabout the axis" of rotation 45 0f the dynamo, ainovement of"; 3

rotation about its own longitudinal axis .6. H5 y i The angle between the plane' of the bladej springs-mid the axis of rotation45 therefore 1 H I I mittedpfrom' the chain wheel to the dynamo shaft 8 through the blade spring 37,fbea1'- o i ings 35 and hub-33 is transmitted through a' Y clutch member of'consta'ntlyvarying rigidity,

the blade spring is at right angles to the axis of rotation 45 and smallest when thesaid' v & 'Besides, V the reduced length of the blade spring is so I adj usted that its maximum value is great in relation to the reduced length of the chain.

dynamo shaft, parts rotatingtherewith and v the crank shaft with the parts rotating there-= with are prevented from attaining a constant natural vibration frequencywhich might be ,inresonance at certain speeds With the vibration creating impulses. On the contrary, the

naturalvibration frequency constantly varies so that the system cannot be set in vibration to acritical extent; The invention is not ments, the said housing being oscillatably mounted on said outermost member, and resilient instrumentalities interposed between sald abutments and connectlngthe' same to said housing. e I v V I 2. A yieldable gearing comprising a driving member having a hub, a slipcoupling mounted on said hub, the said coupling 0.0m prising a plurality of superposed frictional elements provided with downwardly inclined contacting faces,- theoutermost of said elements having radially disposed abutment-s, means for adjusting the frictional contact betweensaidfa ces, a driven member including a housing surrounding said abutments', the said housing being oscillatablymounted onsaid outermost membelfljand resilient vibration dampening means interposed between said abutments and connecting the same to said, housing.

In testimony whereof I aifix my signature.-

VIGGO A; KJAER, 

